The present invention relates to a process for the preparation of 2-Methyl-1,4-naphthoquinone (vitamin K3, xe2x80x9cmenadionexe2x80x9d). The present invention particularly relates to a process for producing 2-Methyl-1,4-naphthoquinone which is used as antihemoragic agent and in animal feed, by the oxidation of 2-Methylnaphthalene with hydrogen peroxide in the presence of acetic acid.
Oxidation is one of the major and industrially important processes and widely 10 used in the synthesis of low and high volume chemicals and pharmaceutical industry. Furthermore, the traditional route of oxidation using mineral acids and inorganic oxides suffer from the disadvantages of high capital cost, reactor corrosion, formation of by product and the difficulty in the catalyst regeneration. In the recent times, scientists worldwide have been devoting their attention to the development of environmentally friendly catalysts and economically feasible routes.
Oxidation of arenes is important in chemical industries, especially in agrochemical and pharmaceutical industries. Many oxidation and hydroxylation reactions were studied using zeolites and redoxmolecular sieves (Sheldon et al. Curr. Opin. Solid: State Mater. Sci. 1, 1996, 101, Sheldon et al. J. Mol. Catal. A 107, 1996, 75; Kumar et al. Synlett. 1995, 289, Arends et al. Angew. Chem. Int. Ed. Eng1. 36, 1997, 1145).
Oxidation of 2-Methylnaphthalene with a sulfuric acid solution of chromic acid was studied (Fieser, J. Biol. Chem., 133, 1940, 391; Sheldon, Top. Curr. Chem., 164, 1993, 21). However, in this stoichiometric oxidation about 18 kg of chromium containing waste is produced for 1 kg of product. Oxidation of 2-Methlynaphthalene was investigated in presence of acetic acid with hydrogen peroxide and methyl trioxo rhenium (Adam et al., Angew. Chem. Int. Ed., 33, 1994, 2475; Herrmann et al., J. Mol. Catal. A Chemical, 138, 1999, 115). Oxidation of 2-Methylnaphthalene was carried over Pd-polystyrenesulfonic acid resin in the acetic acid with hydrogen peroxide (Yamaguchi et al., Chem. Lett., 1985, 827). Metalloporphyrin catalyzed oxidation of 2-Methylnaphthalene by potassium monopersulfate was studied (Song et al, J. Org. Chem., 62, 1997, 673). The oxidation of 2-Methylnaphthalene has been carried out using ammonium persulfate as an oxidizing agent in the presence of cerium (IV) ammonium sulfate and silvernitrate in an emulsified solution (Skarzewski, Tetrahedron, 40, 1984, 4997). The synthesis of vitamin K3 from different starting materials like 1-naphthol, 1,4-naphthoquinone was examined using organic oxidizing agents (Rama Rao et al. Indian J. Chem. 24 B, 1985, 233).
Oxidation of 2-Methylnaphthalene using hydrogen peroxide in the presence of acid catalysts have been claimed in patents (Sugano et al. Ger. Offen DE. 2341463, 1971; Takanobu et al. Japanese kokai 77, 1977, 108959; Baba et al. Japanese kokai 76, 1976, 50147).
The drawbacks of using inorganic oxidants and mineral acids as given in the referred work are: (i) Catalyst can not be reused, (ii) Disposal of acid is not environmentally safe and it is not economical, (iii) Low selectivity is frequently observed, (iv) Corrosion of the reaction vessel and reactors, (v) Not easy to handle and (vi) High inventory of the catalyst.
The main object of the present invention is to develop low cost and ecofriendly route for the oxidation of 2-Methylnaphthalene.
Another object of the present invention is to provide a process for the preparation of 2-Methyl-1,4-naphthoquinone.
Accordingly, the present invention relates to a process for oxidation of 2-Methylnaphthalene with hydrogen peroxide using acetic acid at ambient temperature for at most 3 hours and separating the 2-Methyl-1,4-naphthoquinone from the reaction mixture.
In one embodiment of the invention, the reaction is carried out in the absence of solid catalysts are used.
In another embodiment of the present invention, the reaction is carried out in a temperature range from 60 to 100xc2x0 C.
In another embodiment of the present invention, the reaction is carried out for a period of 1-3 hrs.